Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications...

84
Radar Adaptive Detection and Its Applications Presenter: Jun Liu National Laboratory of Radar Signal Processing Xidian University 2017.11.19 1 EIES 2017

Transcript of Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications...

Page 1: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

Radar Adaptive Detection and Its Applications

Presenter: Jun Liu

National Laboratory of Radar Signal ProcessingXidian University

2017.11.19

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EIES 2017

Page 2: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

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Adaptive detection

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Page 3: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

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Adaptive detection

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Page 4: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

① Adaptive detection: sufficient training data Detector design Statistical analysis

② Adaptive detection: limited training data Detector design Statistical analysis

③ Adaptive detection: no training data Detector design Statistical analysis

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Contents

Page 5: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

① Adaptive detection: sufficient training data

② Adaptive detection: limited training data

③ Adaptive detection: no training data

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Contents

Page 6: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The received data

– s is the steering vector of dimension N £ 1– a is a deterministic but unknown complex scalar– n is disturbance, and has Gaussian distribution with zero mean

and unknown covariance matrix αR, i.e.,– α = 1: homogeneous environment– α ≠ 1: partially homogeneous environment

• A set of training data: • Binary hypothesis testing

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Adaptive Detection With Sufficient Data: Problem Formulation

Page 7: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• According to Neyman-Pearson criterion, the optimal detector is the likelihood ratio test given by

• Due to the unknown parameters, no uniformly most powerful test exists

• This motivates us to design detectors under various criteria

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Adaptive Detection With Sufficient Data: Design Criteria

No uniformly most powerful test

Page 8: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• One-step generalized likelihood ratio test (GLRT)

• Two-step GLRT

• Rao test:

• Wald test:

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Adaptive Detection With Sufficient Data: Design Criteria

Page 9: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Generalized Likelihood Ratio Test– E. J. Kelly, “An adaptive detection algorithm,” IEEE Trans.

Aerosp. Electron. Syst., vol. 22, no. 1, pp. 115–127, Mar. 1986.• Adaptive Matched Filter

– F. C. Robey, D. R. Fuhrmann, E. J. Kelly, and R. Nitzberg, “A CFAR adaptive matched filter detector,” IEEE Trans. Aerosp. Electron. Syst., vol. 28, no. 1, pp. 208–216, Jan. 1992.

• Adaptive Coherence Estimator– S. Kraut, L. L. Scharf, and R. W. Butler, “The adaptive coherent

estimator: A uniformly most-powerful-invariant adaptive detection statistic,” IEEE Trans. Signal Process., vol. 53, no. 2, pp. 427–438, Feb. 2005.

• Rao Test– A. De Maio, “Rao test for adaptive detection in Gaussian

interference with unknown covariance matrix,” IEEE Trans. Signal Process., vol. 55, no. 7, pp. 3577–3584, Jul. 2007.

Adaptive Detection With Sufficient Data: State of the Art

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Page 10: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Homogeneous environment (α = 1):

• Partially homogeneous environment (α ≠ 1)

• These adaptive detectors are designed for rank-1 signal model10

Adaptive Detection With Sufficient Data: Conventional Adaptive Detectors

Page 11: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Signal subspace model:

– S is the steering vector of dimension N £ p, and p < N– a is a deterministic but unknown complex vector of dimension p £ 1– n is disturbance, and has Gaussian distribution with zero mean and

unknown covariance matrix αR, i.e.,– α = 1: homogeneous environment– α ≠ 1: partially homogeneous environment

• A set of training data: • Advantages of signal subspace model

– Robustness– Polarization radar using multiple polarization channels

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Adaptive Detection With Sufficient Data: Signal Subspace Model

Signal subspace model

Page 12: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Binary hypothesis testing for the subspace model case:

• A uniformly most powerful test does not exist• Design detectors under various criteria:

– One-step GLRT– Two-step GLRT– Rao test– Wald test

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Adaptive Detection With Sufficient Data: Signal Subspace Model

Page 13: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Homogeneous environment (α = 1):

• Partially homogeneous environment (α ≠ 1)

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Adaptive Detection With Sufficient Data: Detectors for Subspace Model

Page 14: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The PFA of GLRT detector

• The PD of GLRT detector

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Adaptive Detection With Sufficient Data: Analytical Performance-GLRT

Page 15: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The PFA of AMF detector

• The PD of AMF detector

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Adaptive Detection With Sufficient Data: Analytical Performance-AMF

Page 16: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The PFA of Rao detector

• The PD of Rao detector

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Adaptive Detection With Sufficient Data: Analytical Performance-Rao Test

Page 17: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The PFA of ASD detector

• The PD of ASD detector

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Adaptive Detection With Sufficient Data: Analytical Performance-ASD

Page 18: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Double subspace model:

– X is the received data of N £ K– A is a known matrix of N £ J– C is a known matrix of M £ K– B is an unknown coordinate matrix of J £ M– N is noise matrix of N £ K, each column vector has IID Gaussian

distribution with zero mean and unknown covariance matrix αR• A set of training data:• This data model has many applications in

– Multichannel radar: sensor array, pulsed Doppler radar– MIMO radar– Distributed targets– Multiple-band radar

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Adaptive Detection With Sufficient Data: Further Extension

Page 19: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Special cases in homogeneous environments (α = 1):– N > 1 and J = M = K = 1

multichannel radar– N > 1, J > 1, and M = K = 1

signal subspace model– N > 1, J = 1, and M = K > 1

multiple-band or distributed target– N > 1, J > 1, and M = K > 1

Distributed target detection with uncertain steering vector– N > 1, J > 1, M > 1, K > 1

MIMO radar

• Special cases in partially homogeneous environments (α ≠ 1):– N > 1, J = 1 and M = K >1

Distributed target detection

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Adaptive Detection With Sufficient Data: Further Extension

Page 20: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Adaptive detectors in homogeneous environments (α = 1):

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Adaptive Detection With Sufficient Data: Further Extension

Page 21: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Adaptive detectors in homogeneous environments (α = 1):

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Adaptive Detection With Sufficient Data: Further Extension

Page 22: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Adaptive detectors partially homogeneous environments (α ≠ 1):

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Adaptive Detection With Sufficient Data: Further Extension

Page 23: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Adaptive detectors partially homogeneous environments (α ≠ 1):

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Adaptive Detection With Sufficient Data: Further Extension

Page 24: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Adaptive detectors homogeneous environments (α = 1):

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Adaptive Detection With Sufficient Data: Simulation Results

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Page 25: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Adaptive detectors homogeneous environments (α = 1):

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Adaptive Detection With Sufficient Data: Simulation Results

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Page 26: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Adaptive detector design and performance analysis for the signal subspace model

• Many adaptive detectors are designed for the double subspace signal model

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Adaptive Detection With Sufficient Data: Conclusions

1. Jun Liu, W. Liu, B. Chen, H. Liu, H. Li, and C. Hao, “Modified Rao test for multichannel adaptive signal detection,” IEEE Transactions on Signal Processing, vol. 64, no. 3, pp. 714—725, February 1, 2016.

2. W. Liu, W. Xie, Jun Liu, and Y. Wang, “Adaptive double subspace signal detection in Gaussian background—Part I: homogeneous environments,” IEEE Transactions on Signal Processing, vol. 62, no. 9, pp. 2345—2357, May 2014.

3. W. Liu, W. Xie, Jun Liu, and Y. Wang, “Adaptive double subspace signal detection in Gaussian background—Part II: partially homogeneous environments,” IEEE Transactions on Signal Processing, vol. 62, no. 9, pp. 2358—2369, May 2014.

4. Jun Liu, Z.-J. Zhang and Y. Yang, “Optimal waveform design for generalized likelihood ratio and adaptive matched filter detectors using a diversely polarized antenna,” Signal Processing, vol. 92, no. 4, pp. 1126—1131, Apr. 2012.

5. Jun Liu, Z.-J. Zhang, P.-L. Shui and H. Liu, “Exact performance of an adaptive subspace detector,” IEEE Transactions on Signal Processing, vol. 60, no. 9, pp. 4945—4950, Sep. 2012.

6. Jun Liu, Z.-J. Zhang, Y. Yang and H. Liu, “A CFAR adaptive subspace detector for first-order or second-order Gaussian signals based on a single observation,” IEEE Transactions on Signal Processing, vol. 59, no. 11, pp. 5126—5140, Nov. 2011.

Page 27: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

① Adaptive detection: sufficient training data

② Adaptive detection: limited training data

③ Adaptive detection: no training data

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Contents

Page 28: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Reed, Mallett, and Brenann (RMB) rule:– the SNR loss is 3 dB when the amount of homogeneous

training data used to estimate the noise covariance matrix is approximately twice the dimension of the received signal

K ¼ 2N

• Problems: the number of homogeneous training data is limited

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Page 29: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Diagonal Loading– L. Du, and J. Li, “Fully Automatic Computation of Diagonal

Loading Levels for Robust Adaptive Beamforming,” IEEE Transactions on Aerospace and Electronic Systems, vol. 46, no. 1, January 2010

• Joint Domain Localized Processing– R. S. Adve, T. B. Hale and M. C. Wicks, “Practical joint domain

localised adaptive processing in homogeneous and nonhomogeneous environments. Part 1: Homogeneous environments,” IEE Proc.- Radar, Sonar Navig., vol. 147, No. 2, April 2000

• Knowledge-Aided Methods– J. R. Guerci and E. J. Baranoski, “Knowledge-aided adaptive

radar at DARPA,” IEEE Signal Processing Magazine, vol. 41, January 2006

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Adaptive Detection With Limited Data: The State of Art

Page 30: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Persymmetry exists, when a radar is equipped with a symmetrically spaced linear array for spatial domain processing or symmetrically spaced pulse trains for temporal domain processing

• Persymmetry means double symmetry, for example

• Our focus on convergence rate analysis in the persymmetric case

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Adaptive Detection With Limited Data: Prior Structure on Covariance matrix

11*12

*13

*14

1222*23

*13

132322*12

14131211

SSSSSSSSSSSSSSSS

Persymmetric matrix

11 12 13 14*12 22 23 24* *13 23 33 34* * *14 24 34 44

S S S SS S S SS S S SS S S S

Hermitian

Persymmetry

Page 31: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The received data

– s is the steering vector of dimension N £ 1– a is a deterministic but unknown complex scalar– n is disturbance, and has Gaussian distribution with zero mean

and unknown covariance matrix R, i.e., • The minimum variance distortionless response (MVDR)

beamformer can be obtained by solving the optimization problem:

• The optimal weight vector is

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Adaptive Detection With Limited Data: Convergence Rate

Page 32: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Persymmetric structures– Persymmetric steering vector :– Persymmetric covariance matrix:

• The ML estimate of R with persymmetry (up to a scalar) is

• The persymmetric SMI beamformer in the matched case is given by

• The normalized output SNR of the persymmetric SMI beamformer in the matched case is

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 33: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• In practice, mismatches occur in:– Steering vector: – Covariance matrix:

• The persymmetric SMI beamformer in the mismatched case is

• The normalized output SNR in the mismatched case is

• Problem: what are the average SNR losses in the matched and mismatched cases?

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 34: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Consider the matched case:• We aim to derive the distribution of

• Define

• The ML estimation can be rewritten as

• It is easy to show that

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 35: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Define a unitary transformation

• Two real Gaussian vectors:

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 36: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• From complex domain to real domain

• The normalized output SNR of the persymmetric SMI beamformer can be recast as

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 37: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Using the Bartlett’s decomposition of a real Wishart matrix, we can obtain

• Then

• Recall RMB’s result:•

• The exploitation of persymmetry is equivalent to doubling the number of training data

• In the following we consider the mismatched case

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 38: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• In practice, mismatches occur in:– Steering vector mismatch: – Covariance matrix mismatch:

• The persymmetric SMI beamformer in the mismatched case is

• The normalized output SNR in the mismatched case is

• Problem:

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 39: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• It is very difficult to obtain an exact expression for • Instead, we seek to derive an approximate expression•

where

• Note that when

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 40: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Remark: for

• Hence,• Now, the problem of deriving the average SNR loss turns to

calculate• We prove that

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 41: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Result in the mismatched case:

• One special case:– When

– Recall Boroson’s result:

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Adaptive Detection With Limited Data: Convergence Rate-Our Work

Page 42: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Define• DOA of a target: 400

• DOAs of two interference signals: – 300 and 200

• Matched case:

4220 40 60 80 100 120 140 160

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Adaptive Detection With Limited Data: Convergence Rate-Simulation Results

Page 43: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Mismatched case:

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Adaptive Detection With Limited Data: Convergence Rate-Simulation Results

Page 44: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Mismatched case:

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Adaptive Detection With Limited Data: Convergence Rate-Simulation Results

Page 45: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Persymmetric structures are exploited in adaptive filtering• A distribution of the normalized output SNR of the

persymmetric SMI beamformer is derived • An exact expression for the average SNR loss is obtained

in the matched case• An approximate expression for the average SNR loss is

obtained in the mismatched case:– Mismatch in the steering vector– Mismatched in the covariance matrix

Jun Liu, W. Liu, H. Liu, C. Bo, X.-G. Xia, and F. Dai, “Average SINR calculation of a persymmetricsample matrix inversion beamformer,” IEEE Transactions on Signal Processing, vol. 64, no. 8, pp. 2135—2145, April 15, 2016.

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Adaptive Detection With Limited Data: Convergence Rate-Conclusions

Page 46: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The received data:

– p is the steering vector of dimension m £ 1– a is a deterministic but unknown complex scalar– c is noise, and has Gaussian distribution with zero mean and

unknown covariance matrix M, i.e., • A set of training data for estimating the covariance matrix M

• Persymetric structures– Persymmetric steering vector :– Persymmetric covariance matrix:

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 47: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Binary hypothesis testing

• Use a unitary matrix T to transform the complex steering vector p and the complex covariance matrix M from complexdomain to real domain

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 48: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• After transformation

where

• Note that s and R are both real

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 49: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The maximum likelihood estimate of R is

• The AMF using the persymmetric structures (i.e., P-AMF) becomes

• Note that s and are real, and x is complex

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 50: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The probability of false alarm is derived as

• It is not convenient to use this expression to calculate the detection threshold λ, since an integral is included

• We provide simpler expression to compute the detection threshold

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 51: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Case 1): when m is even and K = m/2, we have M =1/2, and

where

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 52: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Case 2): when m is odd and K = (m+1)/2, we have M =1, and

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 53: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Case 3): to facilitate setting the detection threshold in other cases, the probability of false alarm can be approximated as

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 54: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• There exists a real orthogonal matrix U:

• Define

• Then

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 55: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• It can be shown that

• The P-AMF detector can be equivalently written as

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 56: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Define , its PDF conditioned on ρ is

• When m is odd, the detection probability conditioned on ρ is

• Note that 56

Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 57: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The unconditioned probability of detection for odd m is

• When m is even, M is not an integer. Intuitively, we can approximate the detection probability for m even as the arithmetic mean of the detection probabilities obtained by replacing m with m+1 and m-1

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Adaptive Detection With Limited Data: Persymmetric Adaptive Detection

Page 58: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

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Adaptive Detection With Limited Data: Numerical Results-Simulated Data

Page 59: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

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Adaptive Detection With Limited Data: Numerical Results-Simulated Data

Page 60: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

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se A

larm

m=8, Range #68

MC,K=4MC,K=6MC,K=8theory K=4theory K=6theory,K=8

Adaptive Detection With Limited Data: Numerical Results-Real Data

Page 61: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• PFA = 0.01

61

Adaptive Detection With Limited Data: Numerical Results-Real Data

-10 -5 0 5 10 15 20 25 30 35 400

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SCR(dB)

PD

m = 8, K = 8, Range#15, fd = 0.02

AMFP-AMFCA-CFAR

Page 62: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• PFA = 0.01

62

Adaptive Detection With Limited Data: Numerical Results-Real Data

-10 -5 0 5 10 15 20 25 30 35 400

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SCR(dB)

PD

m = 8, K = 12, Range#15, fd = 0.02

AMFP-AMFCA-CFAR

Page 63: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• PFA = 0.01

63

Adaptive Detection With Limited Data: Numerical Results-Real Data

-10 -5 0 5 10 15 20 25 30 35 400

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SCR(dB)

PD

m = 8, K = 16, Range#15, fd = 0.02

AMFP-AMFCA-CFAR

Page 64: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Persymmetric structures are exploited in adaptive detection• Simpler expressions for the probability of false alarm of the

P-AMF are provided• Closed-form expression for the detection probability of the P-

AMF is derived• The P-AMF outperforms the conventional AMF, especially in

the case of limited training data

64

Jun Liu, G. Cui, H. Li, and B. Himed, “On the performance of a persymmetric adaptive matched filter,” IEEE Transactions on Aerospace and Electronic Systems, vol. 51, no. 4, pp. 2605—2614, October 2015.

Adaptive Detection With Limited Data: Persymmetric Adaptive Detection-Conclusions

Page 65: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

① Adaptive detection: sufficient training data

② Adaptive detection: limited training data

③ Adaptive detection: no training data

65

Contents

Page 66: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Distributed MIMO radar – Spatial diversity

• Collocated MIMO radar– Waveform diversity

Adaptive Detection Without Training Data: MIMO Radar Backgrounds

66

Center

T, R

T, R

Page 67: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• A collocated MIMO radar: M transmit antennas and N receive antennas

• The received data:

– X is the received data of N £ K– ar(θ) is the received steering vector of dimension N £ 1– at(θ) is the transmit steering vector of dimension M £ 1– S is the transmitted waveform matrix of M £ K– a is a deterministic but unknown complex scalar– V is disturbance, and each column vector has IID Gaussian

distribution with zero mean and unknown covariance matrix R• Binary hypothesis testing:

67

Adaptive Detection Without Training Data: Problem Formulation

Page 68: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Known disturbance covariance matrix– I. Bekkerman and J. Tabrikian, “Target detection and localization

using MIMO radars and sonars,” IEEE Transactions on Signal Processing, vol. 54, no. 10, pp. 3873–3883, October 2006.

• Adaptive GLRT detector– L. Xu, J. Li, and P. Stoica, “Target detection and parameter

estimation for MIMO radar systems,” IEEE Transactions on Aerospace and Electronic Systems, vol. 44, no. 3, pp. 927–939, July 2008.

– No statistical analysis for the GLRT detector

Adaptive Detection Without Training Data: State of the Art

68

Page 69: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Rao test:

• Wald test:

• Tunable detector:

69

Adaptive Detection Without Training Data: Proposed Detectors

Page 70: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Probability of false alarm

• Probability of detection in the matched case

70

Adaptive Detection Without Training Data: Analytical Performance

Page 71: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• The nominal receive steering vector deviates from the actual one, and the mismatched angle is defined by

• Probability of detection

71

Adaptive Detection Without Training Data: Analytical Performance-Mismatched Case

Page 72: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Matched case (cos2φ = 0, φ = 0o), M = N =10

72

Adaptive Detection Without Training Data: Numerical Results-Simulated Data

-15 -10 -5 0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SNR (dB)

Det

ectio

n P

roba

bilit

y

(a) K = 1.5N

GLRTα = 0 (i.e., Wald)α = 0.5α = 1 (i.e., Rao)α = 5MC

-15 -10 -5 0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SNR (dB)

Det

ectio

n P

roba

bilit

y

(b) K = 2N

GLRTα = 0 (i.e., Wald)α = 0.5α = 1 (i.e., Rao)α = 5MC

Page 73: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Mismatched case (cos2φ = 0.9412), M = N =10

73

Adaptive Detection Without Training Data: Numerical Results-Simulated Data

-20 -15 -10 -5 0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SNR (dB)

Det

ectio

n P

roba

bilit

y

(a) K = 1.5N

GLRTα = 0 (i.e., Wald)α = 0.5α = 1 (i.e., Rao)α = 5MC

-20 -15 -10 -5 0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SNR (dB)

Det

ectio

n P

roba

bilit

y

(b) K = 2N

GLRTα = 0 (i.e., Wald)α = 0.5α = 1 (i.e., Rao)α = 5MC

Page 74: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Mismatched case, M = N = 10

74

Adaptive Detection Without Training Data: Numerical Results-Simulated Data

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

cos2φ

Det

ectio

n P

roba

bilit

y

(a) SNR = 5 dB

GLRTα = 0 (i.e., Wald)α = 0.1α = 0.5α = 1 (i.e., Rao)α = 2

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

cos2φ

Det

ectio

n P

roba

bilit

y

(b) SNR = 0 dB

GLRTα = 0 (i.e., Wald)α = 0.1α = 0.5α = 1 (i.e., Rao)α = 2

Page 75: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• M = N = 16

75

Adaptive Detection Without Training Data: Numerical Results-Real Data

0 0.02 0.04 0.06 0.08 0.1 0.12 0.1410

-6

10-5

10-4

10-3

10-2

10-1

Threshold

Pro

babi

lity

of fa

lse

alar

m

L = 5

GLRT, theoryGLRT, MCRao test, theoryRao test, MCWald test, theoryWald test, MC

Page 76: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• M = N = 16

76

Adaptive Detection Without Training Data: Numerical Results-Real Data

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.510

-6

10-5

10-4

10-3

10-2

10-1

Threshold

Pro

babi

lity

of fa

lse

alar

m

L = 10

GLRT, theoryGLRT, MCRao test, theoryRao test, MCWald test, theoryWald test, MC

Page 77: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• M = N = 16

77

Adaptive Detection Without Training Data: Numerical Results-Real Data

Page 78: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• M = N = 16

78

Adaptive Detection Without Training Data: Numerical Results-Real Data

Page 79: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• M = N = 16

79

Adaptive Detection Without Training Data: Numerical Results-Real Data

Page 80: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• M = N = 16

80

Adaptive Detection Without Training Data: Numerical Results-Real Data

Page 81: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• M = N = 16

81

Adaptive Detection Without Training Data: Numerical Results-Real Data

0 4 8 12 16 20 24 28 320

0.1

0.2

0.3

0.4

0.5

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0.8

0.9

1

SNR(dB)

PD

N = 16, L = 10, fd=0.02

GLRTRaoWaldCA-CFAR

Page 82: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• M = N = 16

82

Adaptive Detection Without Training Data: Numerical Results-Real Data

0 4 8 12 16 20 24 28 320

0.1

0.2

0.3

0.4

0.5

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0.8

0.9

1

SNR(dB)

PD

N = 16, L = 5, fd = 0.02

GLRTRaoWaldCA-CFAR

Page 83: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

• Rao test, Wald test, and tunable detector are proposed in collocated MIMO radar

• Training data is not required for the adaptive detection• All three detectors exhibit CFAR against clutter covariance

matrix• Analytical expressions for the PFA and PD are derived for both

matched and mismatched cases

83

1. W. Liu, Y. Wang, Jun Liu, W. Xie, H. Chen, and W. Gu, “Adaptive detection without training data in collocated MIMO Radar,” IEEE Transactions on Aerospace and Electronic Systems, vol. 51, no. 3, pp. 2469—2479, July 2015.

2. Jun Liu, S. Zhou, W. Liu, J. Zheng, H. Liu, and J. Li, “Tunable adaptive detection in collocated MIMO Radar,” IEEE Transactions on Signal Processing, Accepted for publication.

Adaptive Detection Without Training Data: Conclusions

Page 84: Radar Adaptive Detection and Its Applications · Radar Adaptive Detection and Its Applications Presenter: Jun Liu ... – MIMO radar – Distributed targets – Multiple-band radar

Thank you!

84